Optical disk apparatus

1. An optical disc apparatus for recording information on an optical disc which has at least two recording layers including layer 0 and layer 1 reproducible from one side of the disc, wherein each layer has a plurality of sectors, the apparatus comprising: an optical pickup having a laser source from which an optical beam emanates, an objective lens which concentrates the optical beam on a recording layer, and an actuator which moves the objective lens in the direction of the thickness of the disc, wherein a focal point of the objective lens is focused on one layer of the two recording layers; and a controller which obtains a present layer information of a sector recording layer, on which information is recorded, from light reflected from the disc; which confirms a target layer information of a target recording layer for information to be recorded; which judges whether the present layer information is the same as the target layer information; and which outputs a first control signal to the actuator when it is judged that the present layer information is layer 0 and the target layer information is layer 1 , and which outputs a second control signal to a slider; wherein the actuator moves the objective lens in the direction of the thickness of the disc in response to the first control signal to the actuator until the focal point of the objective lens is focused on layer 1 ; and wherein said slider moves the optical pickup target position in response to the second control signal to the slider after the focal point of the objective lens is moved to layer 1 .

2. An optical disc apparatus for recording information on an optical disc which has at least two recording layers including layer 0 and layer 1 reproducible from one side of the disc, wherein each layer has a plurality of sectors, the apparatus comprising: a laser source from which an optical beam emanates; an objective lens which concentrates the optical beam on a recording layer; an actuator which moves the objective lens in the direction of the thickness of the disc, wherein a focal point of the objective lens is focused on one layer of the two recording layers; a light detector which detects a light reflected from the disc; a controller which obtains a present layer information of a sector of the recording layer, on which information is recorded from the reflected light, which confirms a target layer information of a target recording layer for information to be recorded, and which outputs a control signal to the actuator when said present layer information is layer 0 and the target layer information is layer 1 ; and wherein the actuator moves the objective lens in the direction of the thickness of the disc in response to the control signal until the focal point of the objective lens is focused on layer 1 .

3. An optical disc apparatus for recording information on an optical disc which has at least two recording layers including layer 0 and layer 1 reproducible from one side of the disc, wherein each layer has a plurality of sectors, the apparatus comprising: an optical pickup which irradiates an optical beam on a recording layer by moving a focal point of the optical beam and which detects a light reflected from the disc; a controller which obtains a present layer information of a sector of the recording layer being reproduced from the reflected light, which confirms a target layer information of a target recording layer on which information is to be recorded, and which outputs a control signal to the optical pickup when the present layer information is layer 0 and the target layer information is layer 1 ; and wherein the optical pickup moves the focal point of the optical beam in the direction of the thickness of the disc in response to the control signal so that optical beam is focused on layer 1 .

4. An optical disc apparatus for reproducing information recording on an optical disc which has at least two recording layers including layer 0 and layer 1 reproducible from one side of the disc, wherein each layer has a plurality of sectors, the apparatus comprising: a laser source from which an optical beam emanates; an objective lens which concentrates the optical beam on a recording layer; an actuator which moves the objective lens in the direction of the thickness of the disc; a controller which obtains a present layer information of a sector of the recording layer being reproduced from light reflected from the disc, which confirms a target layer information indicating the recording layer which includes information to be reproduced, and which outputs a control signal to the actuator when the present layer information is layer 0 and the target layer information is layer 1 ; and wherein the actuator moves the objective lens in the direction of the thickness of the disc in response to the control signal until the focal point of the objective lens is focused on layer 1 .

5. An optical disc apparatus for reproducing information recorded on an optical disc which has at least two recording layers including layer 0 and layer 1 reproducible from one side of the disc, wherein each layer has a plurality of sectors, the apparatus comprising: an optical pickup which irradiates an optical beam on a recording layer by moving a focal point of the optical beam and which detects a light reflected from the disc; a controller which obtains a present layer information of a sector of the recording layer being reproduced from the reflected light, which confirms a target layer information of a target recording layer which has a target information, and which outputs a control signal to the optical pickup when the present layer information is layer 0 and the target lager information is layer 1 ; and wherein the optical pickup moves the focal point of the optical beam in the direction of the thickness of the disc in response to the control signal so that the optical beam is focused on layer 1 .